RBC Disorders Flashcards
WHO definition of anemia
Hb < 13 g/dL in men
Hb < 12 g/dL in women
Hb and Hct are important to consider in anemic pts because certain conditions may yield low Hb levels with a normal Hct — what is an example of a condition that does this?
Thalassemia
When Hb levels do not approximate 1/3 of Hct, what are some other lab findings to check for?
High leukocyte counts Lipemia Precipitating monoclonal proteins Cold agglutinins Hyperglycemia
Normocytic anemias with primarily extravascular hemolysis
Hereditary spherocytosis
Sickle cell anemia
Hemoglobin C
Normocytic anemias with predominantly intravascular hemolysis
Paroxysmal nocturnal hemoglobinuria
G6PD deficiency
Immune hemolytic anemia
Microangiopathic hemolytic anemia
Anemias due to underproduction
Aplastic anemia (drugs, chemicals, viral infxn, autoimmune damage)
Myelophthisic process
Causes of microcytic hypochromic anemia
Iron deficiency
Inflammatory block to iron utilization
Thalassemia
Sideroblastic
Causes of macrocytic anemia
Stress erythropoiesis (accompanied by high retic count)
Nonmegaloblastic causes = liver disease, asplenia, hyposplenia, hypothyroid
Megaloblastic causes = B12 deficiency, folate deficiency, certain drugs, alcohol myelodysplasia
In what types of anemia would you see hyperchromic cells?
Disorders that lead to increased Hb per RBC and/or Hct, implying loss of RBC membrane in relation to RBC volume — occurs in HEMOLYTIC anemias and certain HEMOGLOBINOPATHIES
What lab is used to determine whether bone marrow response to anemia is adequate?
Reticulocyte count
Anemia in the setting of appropriately increased retic counts (>100,000/microliter) almost always reflect what cause(s) of the anemia?
Erythrocyte loss (bleeding, hemolysis)
Also occurs as a response to therapy (iron, folate, B12
Anemia in the setting of low retic count) indicates what cause(s) of the anemia?
Erythrocyte underproduction d/t deficient erythropoietin — includes the nutritional deficiencies (B12, folate, iron)
Leading cause, symptoms, and peripheral blood findings in aplastic anemia
Leading cause = autoimmune (other cause is drug-induced marrow suppression)
Symptoms occur d/t underlying pancytopenia — fatigue, dyspnea, bleeding, infection
PB shows anemia, thrombocytopenia, leukopenia
Management of aplastic anemia
Allogeneic HCT in pts <40 and otherwise healthy
Pts not eligible should receive immunosuppressive therapy with antithymocyte globulin and cyclosporin
PB smear findings w/iron deficiency anemia
Hypochromia (increased central pallor)
Anisocytosis
Poikilocytosis
Lab test most useful for dx of iron deficiency anemia
Serum ferritin
[decreased serum ferritin, increased TIBC, decreased serum iron, decreased %sat, increased FEP]
Tx of choice for iron deficiency anemia
Oral Ferrous sulfate
Loss of vibration or position sense in the setting of macrocytic anemia might indicate _____
Cobalamin (B12 deficiency)
Risk factors for folate deficiency
Excess alcohol use, poor diet, small-bowel disease, consider eval for celiac
PB findings and type of anemia associated with CKD
Echinocytes (erythrocytes w/small number of spicules of uniform size and distribution on cell surface)
Normocytic anemia w/Low retic count
How are ferritin, TIBC, and serum iron levels altered in anemia of chronic disease?
Increased ferritin
Decreased TIBC
Decreased serum iron
_______ seen on PB smear are evidence of fragmentation hemolysis due to things like DIC, TTP, or malfunctioning heart valve
Schistocytes
____ on peripheral smear often indicate immune hemolytic anemia
Spherocytes
Cold agglutinin autoimmune hemolytic anemia is confirmed by what diagnostic tests?
Direct Coombs test positive for C3
Cold agglutinin titers
Peripheral smear findings of target cells, teardrop cells, and/or basophilic stippling indicate what hemoglobinopathy?
Thalassemia
Which of the following is true of beta-thalassemia?
A. Increased HbS B. Increased HbA2 C. Decreased HbS D. Decreased HbA2 E. Decreased HbF
B. Increased HbA2
T/F: alpha thalassemia is not associated with diagnosis of structural Hb abnormality, but instead is diagnosed based on Hct, MCV, blood smear, and family study
True
A high serum creatinine in the setting of anemia indicates what?
Underproduction of erythropoietin by the kidneys
TSH is used to check for _____ which may cause anemia
Hypothyroidism
Serum testosterone is used to assess for _____ in men, which may cause anemia
Hypotestosteronism
Haptoglobin levels <20 mg/dL indicate _______, supported by elevated LDH and total bilirubin levels
Hemolysis
Presence of urine hemosiderin and hemoglobin indicate ______
Intravascular hemolysis
Precipitating factors in sickle cell anemia
Sickle mutation = single base change GAT—>GTT (glutamate to valine) in 6th codon of exon 1 of B-globin gene
More common in African, Hispanic, Mediterranean, Asian, and Indian descent
Pathophysiologic process by which Hb S causes sickling
When Hb S becomes deoxygenated, heterotetramers polymerize to form fibrils that sickle and hemolyze
S/s of sickle cell disease
Manifests at 6 months
Recurring episodes of acute pain, chronic pain, and s/s of anemia
Avg hemoglobin is 7-8 with high retic count
PE findings may include fever, tachycardia, RR 16-20, BP low normal, systolic murmur, small fibrotic spleen, leg ulcers
Treatment for sickle cell disease
Hydroxyurea ACE inhibitors Folic acid Pain relievers Vaccinations to prevent infection
Crises associated with sickle cell disease
Acute chest syndrome — vasoocclusion in pulmonary microcirculation; presents with chest pain, SOB, lung infiltrates, may be preceded by PNA; MCC of death in adults
Pain crises
Renal papillary necrosis — gross hematuria and proteinuria
Hepatic crisis — tender hepatomegaly
Lab and PE findings associated with hemolytic anemia d/t plasmodium spp.
Parasites in RBCs on PB
Sxs of infection — fever
Splenomegaly!!
Lab and PE findings associated with hemolytic anemia d/t Babesia microti
Parasites in RBCs on PB
Sxs of infection — fever
Milder malaria like illness unless pt is asplenic
The diagnosis of __________ is confirmed by a positive osmotic fragility test and a negative direct antiglobulin (coombs) test
Hereditary spherocytosis
Hereditary spherocytosis is associated with a positive family history as well as what PE and lab findings?
PE — splenomegaly
PB smear — spherocytes
